Preparation and use of 2-substituted-5-oxo-3-pyrazolidinecarboxylates

ABSTRACT

A method is disclosed for preparing a 2-substituted-5-oxo-3-pyrazolidinecarboxylate compound of Formula I. The method comprises contacting a succinic acid derivative of the formula R 1 OC(O)C(H)(X)C(R 2a )(R 2b )C(O)Y (i.e. Formula II) wherein X and Y are leaving groups and L, R 1 , R 2a  and R 2b  are as defined in the disclosure, with a substituted hydrazine of the formula LNHNH 2  (i.e. Formula III) in the presence of a suitable acid scavenger and solvent. Also disclosed is the preparation of compounds of Formula IV wherein X 1 , R 6 , R 7 , R 8a , R 8b , R 9 , and n are as defined in the disclosure. Also disclosed is a composition comprising on a weight basis about 20 to 99% of the compound of Formula II wherein R 1 , R 2a , R 2b , R 3 , R 4  and R 5  are as defined in the disclosure; X is Cl, Br or I; and Y is F, Cl, Br or I; provided that when R 2a  and R 2b  are each H, and X and Y are each Cl then R 1  is other than benzyl and when R 2a  and R 2b  are each phenyl, and X and Y are each Cl, then R 1  is other than methyl or ethyl. Also disclosed is a crystalline composition comprising at least about 90% by weight of the compound of the formula R 1 OC(O)C(H)(X)C(R 2a )(R 2b )CO 2 H (i.e. Formula VI) wherein R 2a  and R 2b  are H, X is Br and R 1  is methyl.

BACKGROUND OF THE INVENTION

A need exists for additional methods to prepare2-substituted-5-oxo-3-pyrazolidinecarboxylates. Such compounds includeuseful intermediates for the preparation of crop protection agents,pharmaceuticals, photographic developers and other fine chemicals. U.S.Pat. No. 3,153,654 and PCT Publication WO 03/015519 describe thepreparation of 2-substituted-5-oxo-3-pyrazolidinecarboxylates bycondensation of maleate or fumarate esters with substituted hydrazinesin the presence of a base. However, alternative methods providingpotentially greater yields are still needed.

SUMMARY OF THE INVENTION

This invention relates to a method for preparing a2-substituted-5-oxo-3-pyrazolidinecarboxylate compound of Formula I

wherein

-   -   L is H, optionally substituted aryl, optionally substituted        tertiary alkyl, —C(O)R³, —S(O)₂R³ or —P(O)(R³)₂;    -   R¹ is an optionally substituted carbon moiety;    -   R^(2a) is H, OR⁴ or an optionally substituted carbon moiety;    -   R^(2b) is H or an optionally substituted carbon moiety;    -   each R³ is independently OR⁵, N(R⁵)₂ or an optionally        substituted carbon moiety;    -   R⁴ is an optionally substituted carbon moiety; and    -   each R⁵ is selected from optionally substituted carbon moieties;        the method comprising contacting a succinic acid derivative of        Formula II        wherein    -   X is a leaving group; and    -   Y is a leaving group;    -   with a substituted hydrazine of Formula III        LNHNH₂   III        in the presence of a suitable acid scavenger and solvent.

This invention also relates to a method of preparing a compound ofFormula IV,

wherein

-   -   X¹ is halogen;    -   R⁶ is CH₃, F, Cl or Br;    -   R⁷ is P, Cl, Br, I, CN or CF₃;    -   R^(8a) is H or C₁-C₄ alkyl;    -   R^(8b) is H or CH₃;    -   each R⁹ is independently C₁-C₄ alkyl, C₂-C₄ alkenyl, C₂-C₄        alkynyl, C₃-C₆ cycloalkyl, C₁-C₄ haloalkyl, C₂-C₄ haloalkenyl,        C₂-C₄ haloalkynyl, C₃-C₆ halocycloalkyl, halogen, CN, NO₂, C₁-C₄        alkoxy, C₁-C₄ haloalkoxy, C₁-C₄ alkylthio, C₁-C₄ alkylsulfinyl,        C₁-C₄ alkylsulfonyl, C₁-C₄ alkylamino, C₂-C₈ dialkylamino, C₃-C₆        cycloalkylamino, (C₁-C₄ alkyl)(C₃-C₆ cycloalkyl)amino, C₂-C₄        alkylcarbonyl, C₂-C₆ alkoxycarbonyl, C₂-C₆ alkylaminocarbonyl,        C₃-C₈ dialkylaminocarbonyl or C₃-C₆ trialkylsilyl;    -   Z is N or CR¹⁰;    -   R¹⁰ is H or R⁹; and    -   n is an integer from 0 to 3        using a compound of Formula Ia    -   wherein R¹ is an optionally substituted carbon moiety.        This method is characterized by preparing the compound of        Formula Ia (i.e. a subgenus of Formula I) by the method as        indicated above.

This invention further provides a composition comprising on a weightbasis about 20 to 99% of the compound of Formula II wherein R¹, R^(2a),R^(2b), R³, R⁴ and R⁵ are as above; X is Cl, Br or I; and Y is F, Cl, Bror I; provided that when R^(2a) and R^(2b) are each H, and X and Y areeach Cl then R¹ is other than benzyl and when R^(2a) and R^(2b) are eachphenyl, and X and Y are each Cl, then R¹ is other than methyl or ethyl.

This invention further provides a crystalline composition comprising atleast about 90% by weight of the compound of Formula VI

-   -   wherein R^(2a) and R^(2b) are H, X is Br and R¹ is methyl.

DETAILED DESCRIPTION OF THE INVENTION

In the recitations herein, the term “carbon moiety” refers to a radicalcomprising a carbon atom linking the radical to the remainder of themolecule. As the substituents R¹, R^(2a), R^(2b), R³, R⁴ and R⁵ areseparated from the reaction center, they can encompass a great varietyof carbon-based groups preparable by modern methods of synthetic organicchemistry. Also the substituent L can encompass in addition to hydrogena wide range of radicals selected from optionally substituted aryl,optionally substituted tertiary alkyl, —C(O)R³, —S(O)₂R³ or —P(O)(R³)₂,which stereoelectronically align with the cyclization regiochemistry ofthe method of the present invention. The method of this invention isthus generally applicable to a wide range of starting compounds ofFormula II and product compounds of Formula I.

“Carbon moiety” thus includes alkyl, alkenyl and alkynyl, which can bestraight-chain or branched. “Carbon moiety” also includes carbocyclicand heterocyclic rings, which can be saturated, partially saturated, orcompletely unsaturated. Furthermore, unsaturated rings can be aromaticif Hückel's rule is satisfied. The carbocyclic and heterocyclic rings ofa carbon moiety can form polycyclic ring systems comprising multiplerings connected together. The term “carbocyclic ring” denotes a ringwherein the atoms forming the ring backbone are selected only fromcarbon. The term “heterocyclic ring” denotes a ring wherein at least oneof the ring backbone atoms is other than carbon. “Saturated carbocyclic”refers to a ring having a backbone consisting of carbon atoms linked toone another by single bonds; unless otherwise specified, the remainingcarbon valences are occupied by hydrogen atoms. The term “aromatic ringsystem” denotes fully unsaturated carbocycles and heterocycles in whichat least one ring in a polycyclic ring system is aromatic. Aromaticindicates that each of ring atoms is essentially in the same plane andhas a p-orbital perpendicular to the ring plane, and in which (4n+2) πelectrons, when n is 0 or a positive integer, are associated with thering to comply with Hückel's rule. The term “aromatic carbocyclic ringsystem” includes fully aromatic carbocycles and carbocycles in which atleast one ring of a polycyclic ring system is aromatic. The term“nonaromatic carbocyclic ring system” denotes fully saturatedcarbocycles as well as partially or fully unsaturated carbocycleswherein none of the rings in the ring system are aromatic. The terms“aromatic heterocyclic ring system” and “heteroaromatic ring” includefully aromatic heterocycles and heterocycles in which at least one ringof a polycyclic ring system is aromatic. The term “nonaromaticheterocyclic ring system” denotes fully saturated heterocycles as wellas partially or fully unsaturated heterocycles wherein none of the ringsin the ring system are aromatic. The term “aryl” denotes a carbocyclicor heterocyclic ring or ring system in which at least one ring isaromatic, and the aromatic ring provides the connection to the remainderof the molecule.

The carbon moieties specified for R¹, R^(2a), R^(2b), R³, R⁴ and R⁵ andthe aryl and tertiary alkyl radicals specified for L are optionallysubstituted. The term “optionally substituted” in connection with thesecarbon moieties refers to carbon moieties that are unsubstituted or haveat least one non-hydrogen substituent. Similarly, the term “optionallysubstituted” in connection with aryl and tertiary aryl refers to aryland tertiary alkyl radicals that are unsubstituted or have a least onnon-hydrogen substituent. Illustrative optional substituents includealkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, hydroxycarbonyl, formyl,alkylcarbonyl, alkenylcarbonyl, alkynylcarbonyl, alkoxycarbonyl,hydroxy, alkoxy, alkenyloxy, alkynyloxy, cycloalkoxy, aryloxy,alkylthio, alkenylthio, alkynylthio, cycloalkylthio, arylthio,alkylsulfinyl, alkenylsulfinyl, alkynylsulfinyl, cycloalkylsulfinyl,arylsulfinyl, alkylsulfonyl, alkenylsulfonyl, alkynylsulfonyl,cycloalkylsulfonyl, arylsulfonyl, amino, alkylamino, alkenylamino,alkynylamino, arylamino, aminocarbonyl, alkylaminocarbonyl,alkenylaminocarbonyl, alkynylaminocarbonyl, arylaminocarbonyl,alkylaminocarbonyl, alkenylaminocarbonyl, alkynylaminocarbonyl,arylaminocarbonyloxy, alkoxycarbonylamino, alkenyloxycarbonylamino,alkynyloxycarbonylamino and aryloxy-carbonylamino, each furtheroptionally substituted; and halogen, cyano and nitro. The optionalfurther substituents are independently selected from groups like thoseillustrated above for the substituents themselves to give additionalsubstituent radicals for L, R¹, R^(2a), R^(2b), R³, R⁴ and R⁵ such ashaloalkyl, haloalkenyl and haloalkoxy. As a further example, alkylaminocan be further substituted with alkyl, giving dialkylamino. Thesubstituents can also be tied together by figuratively removing one ortwo hydrogen atoms from each of two substituents or a substituent andthe supporting molecular structure and joining the radicals to producecyclic and polycyclic structures fused or appended to the molecularstructure supporting the substituents. For example, tying togetheradjacent hydroxy and methoxy groups attached to, for example, a phenylring gives a fused dioxolane structure containing the linking group—O—CH₂—O—. Tying together a hydroxy group and the molecular structure towhich it is attached can give cyclic ethers, including epoxides.Illustrative substituents also include oxygen, which when attached tocarbon forms a carbonyl function. Similarly, sulfur when attached tocarbon forms a thiocarbonyl function. Within the L, R¹, R^(2a), R^(2b),R³, R⁴ or R⁵ moieties, tying together substituents can form cyclic andpolycyclic structures. Also illustrative of R¹, R^(2a) and R^(2b) areembodiments wherein at least two of the R¹, R^(2a) and R^(2b) moietiesare contained in the same radical (i.e. a ring system is formed). As thepyrazolidine moiety constitutes one ring, the R¹ moiety contained in thesame radical as R^(2a) (or OR⁴) or R^(2b) would result in a fusedbicyclic or polycyclic ring system. Two R^(2a) and R^(2b) moietiescontained in the same radical would result in a spiro ring system.

As referred to herein, “alkyl”, used either alone or in compound wordssuch as “alkylthio” or “haloalkyl” includes straight-chain or branchedalkyl, such as, methyl, ethyl, n-propyl, i-propyl, or the differentbutyl, pentyl or hexyl isomers. “Tertiary alkyl” denotes a branchedalkyl radical wherein the carbon atom linked to the remainder of themolecule is also attached to three carbon atoms in the radical. Examplesof “tertiary alkyl” include —C(CH₃)₃, —C(CH₃)₂CH₂CH₃ and—C(CH₃)(CH₂CH₃)(CH₂)₂CH₃. “Alkenyl” includes straight-chain or branchedalkenes such as ethenyl, 1-propenyl, 2-propenyl, and the differentbutenyl, pentenyl and hexenyl isomers. “Alkenyl” also includes polyenessuch as 1,2-propadienyl and 2,4-hexadienyl. “Alkynyl” includesstraight-chain or branched alkynes such as ethynyl, 1-propynyl,2-propynyl and the different butynyl, pentynyl and hexynyl isomers.“Alkynyl” can also include moieties comprised of multiple triple bondssuch as 2,5-hexadiynyl. “Alkoxy” includes, for example, methoxy, ethoxy,n-propyloxy, isopropyloxy and the different butoxy, pentoxy and hexyloxyisomers. “Alkenyloxy” includes straight-chain or branched alkenyloxymoieties. Examples of “alkenyloxy” include H₂C═CHCH₂O, (CH₃)₂C═CHCH₂O,(CH₃)CH═CHCH₂O, (CH₃)CH═C(CH₃)CH₂O and CH₂═CHCH₂CH₂O. “Alkynyloxy”includes straight-chain or branched alkynyloxy moieties. Examples of“alkynyloxy” include HC≡CCH₂O, CH₃C≡CCH₂O and CH₃C≡CCH₂CH₂O. “Alkylthio”includes branched or straight-chain alkylthio moieties such asmethylthio, ethylthio, and the different propylthio, butylthio,pentylthio and hexylthio isomers. “Alkylsulfinyl” includes bothenantiomers of an alkylsulfinyl group. Examples of “alkylsulfinyl”include CH₃S(O), CH₃CH₂S(O), CH₃CH₂CH₂S(O), (CH₃)₂CHS(O) and thedifferent butylsulfinyl, pentylsulfinyl and hexylsulfinyl isomers.Examples of “alkylsulfonyl”include CH₃S(O)₂, CH₃CH₂S(O)₂,CH₃CH₂CH₂S(O)₂, (CH₃)₂CHS(O)₂ and the different butylsulfonyl,pentylsulfonyl and hexylsulfonyl isomers. “Alkylamino”, “alkenylthio”,“alkenylsulfinyl”, “alkenylsulfonyl”, “alkynylthio”, “alkynylsulfinyl”,“alkynylsulfonyl”, and the like, are defined analogously to the aboveexamples. Examples of “alkylcarbonyl” include C(O)CH₃, C(O)CH₂CH₂CH₃ andC(O)CH(CH₃)₂. Examples of “alkoxycarbonyl” include CH₃OC(═O),CH₃CH₂OC(═O), CH₃CH₂CH₂OC(═O), (CH₃)₂CHOC(═O) and the different butoxy-or pentoxycarbonyl isomers. “Cycloalkyl” includes, for example,cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. The term“cycloalkoxy” includes the same groups linked through an oxygen atomsuch as cyclopentyloxy and cyclohexyloxy. “Cycloalkylamino” means theamino nitrogen atom is attached to a cycloalkyl radical and a hydrogenatom and includes groups such as cyclopropylamino, cyclobutylamino,cyclopentylamino and cyclohexylamino. “(Alkyl)(cycloalkyl)amino” means acycloalkylamino group where the hydrogen atom is replaced by an alkylradical; examples include groups such as (methyl)(cyclopropyl)amino,(butyl)(cyclobutyl)amino, (propyl)cyclopentylamino,(methyl)cyclohexylamino and the like. “Cycloalkenyl” includes groupssuch as cyclopentenyl and cyclohexenyl as well as groups with more-thanone double bond such as 1,3- and 1,4-cyclohexadienyl.

The term “halogen”, either alone or in compound words such as“haloalkyl”, includes fluorine, chlorine, bromine or iodine. The term“1-2 halogen” indicates that one or two of the available positions forthat substituent may be halogen which are independently selected.Further, when used in compound words such as “haloalkyl”, said alkyl maybe partially or fully substituted with halogen atoms which may be thesame or different. Examples of “haloalkyl” include F₃C, ClCH₂, CF₃CH₂and CF₃CCl₂.

The term “sulfonate” refers to radicals comprising a —OS(O)₂— whereinthe sulfur atom is bonded to a carbon moiety, and the oxygen atom isbonded to the remainder of the molecule and thus serves as theattachment point for the sulfonate radical. Commonly used sulfonatesinclude —OS(O)₂Me, —OS(O)₂Et, —OS(O)₂-n-Pr, —OS(O)₂CF₃, —OS(O)₂Ph and—S(O)₂Ph-4-Me.

The total number of carbon atoms in a substituent group is indicated bythe “C_(i)-C_(j)” prefix where i and j are, for example, numbers from 1to 3; e.g., Cl-C₃ alkyl designates methyl through propyl.

Although there is no definite limit to the sizes of Formulae I, II andIII suitable for the rocesses of the invention, typically Formula Icomprises 5-100, more commonly 5-50, and most commonly 5-25 carbonatoms, and 5-25, more commonly 5-15, and most commonly 5-10 heteroatoms.Typically Formula II comprises 5-50, more commonly 5-25, and mostcommonly 5-12 carbon atoms, and 5-15, more commonly 5-10, and mostcommonly 5-7 heteroatoms. Typically Formula III comprises 0-50, morecommonly 6-25, and most commonly 6-13 carbon atoms, and 2-12, morecommonly 2-7, and most commonly 2-5 heteroatoms. The heteroatoms arecommonly selected from halogen, oxygen, sulfur, nitrogen and phosphorus.Three heteroatoms in Formulae I and II are the two oxygen atoms in thecarboxylate ester group (R¹OC(O)—) and the oxygen atom in the othercarbonyl radical. Two heteroatoms in Formulae I and III are the twonitrogen atoms in the pyrazoline ring and the precursor hydrazine. X andY typically each comprise at least one heteroatom.

Although there is no definite limit to the size of R¹, R^(2a), R^(2b),R³, R⁴ and R⁵, optionally substituted alkyl moieties of R¹, R^(2a),R^(2b), R³, R⁴ and R⁵ commonly include 1 to 6 carbon atoms, morecommonly 1 to 4 carbon atoms and most commonly 1 to 2 carbon atoms inthe alkyl chain. Optionally substituted alkenyl and alkynyl moieties ofR¹, R^(2a), R^(2b), R³, R⁴ and R⁵ commonly include 2 to 6 carbon atoms,more commonly 2 to 4 carbon atoms and most commonly 2 to 3 carbon atomsin the alkenyl or alkynyl chain. Optionally substituted tertiary alkylmoieties of L commonly include 4 to 10 carbon atoms, more commonly 4 to8 carbon atoms and most commonly 4 to 6 carbon atoms.

As indicated above, the carbon moieties of R¹, R^(2a), R^(2b), R³, R⁴and R⁵ may be (among others) an aromatic ring or ring system. Also thearyl moiety of L is an aromatic ring or ring system. Examples ofaromatic rings or ring systems include a phenyl ring, 5- or 6-memberedheteroaromatic rings, aromatic 8-, 9- or 10-membered fused carbobicyclicring. systems and aromatic 8-, 9- or 10-membered fused heterobicyclicring systems wherein each ring or ring system is optionally substituted.The term “optionally substituted” in connection with these R¹, R^(2a),R^(2b), R³, R⁴ and R⁵ carbon moieties and the aryl moiety of L refers tocarbon moieties which are unsubstituted or have at least onenon-hydrogen substituent. These carbon moieties may be substituted withas many optional substituents as can be accommodated by replacing ahydrogen atom with a non-hydrogen substituent on any available carbon ornitrogen atom. Commonly, the number of optional substituents (whenpresent) ranges from one to four. An example of phenyl optionallysubstituted with from one to four substituents is the ring illustratedas U-1 in Exhibit 1, wherein R^(v) is any non-hydrogen substituent and ris an integer from 0 to 4. Examples of aromatic 8-, 9- or 10-memberedfused carbobicyclic ring systems optionally substituted with from one tofour substituents include a naphthyl group optionally substituted withfrom one to four substituents illustrated as U-85 and a1,2,3,4-tetrahydronaphthyl group optionally substituted with from one tofour substituents illustrated as U-86 in Exhibit 1, wherein R^(v) is anysubstituent and r is an integer from 0 to 4. Examples of 5- or6-membered heteroaromatic rings optionally substituted with from one tofour substituents include the rings U-2 through U-53 illustrated inExhibit 1 wherein R^(v) is any substituent and r is an integer from 1 to4. Examples of aromatic 8-, 9- or 10-membered fused heterobicyclic ringsystems optionally substituted with from one to four substituentsinclude U-54 through U-84 illustrated in Exhibit 1 wherein R^(v) is anysubstituent, for example a substituent such as R⁹, and r is an integerfrom 0 to 4. Other examples of L, R¹, R^(2a), R^(2b), R³, R⁴ and R⁵include a benzyl group optionally substituted with from one to foursubstituents illustrated as U-87 and a benzoyl group optionallysubstituted with from one to four substituents illustrated as U-88 inExhibit 1, wherein R^(v) is any substituent and r is an integer from 0to 4.

Although R^(v) groups are shown in the structures U-1 through U-85, itis noted that they do not need to be present since they are optionalsubstituents. The nitrogen atoms that require substitution to fill theirvalence are substituted with H or R^(v). Note that some U groups canonly be substituted with less than 4 R^(v) groups (e.g., U-14, U-15,U-18 through U-21 and U-32 through U-34 can only be substituted with oneR^(v)). Note that when the attachment point between (R^(v))_(r) and theU group is illustrated as floating, (R^(v))_(r) can be attached to anyavailable carbon atom or nitrogen atom of the U group. Note that whenthe attachment point on the U group is illustrated as floating, the Ugroup can be attached to the remainder of Formulae I, II and III throughany available carbon of the U group by replacement of a hydrogen atom.

As indicated above, the carbon moieties of R¹, R^(2a), R^(2b), R³, R⁴and R⁵ may be (among others) saturated or partially saturatedcarbocyclic and heterocyclic rings, which can be further optionallysubstituted. The term “optionally substituted” in connection with theseR¹, R^(2a), R^(2b), R³, R⁴ and R⁵ carbon moieties refers to carbonmoieties which are unsubstituted or have at least one non-hydrogensubstituent. These carbon moieties may be substituted with as manyoptional substituents as can be accommodated by replacing a hydrogenatom with a non-hydrogen substituent on any available carbon or nitrogenatom. Commonly, the number of optional substituents (when present)ranges from one to four. Examples of saturated or partially saturatedcarbocyclic rings include optionally substituted C₃-C₈ cycloalkyl andoptionally substituted C₃-C₈ cycloalkyl. Examples of saturated orpartially saturated heterocyclic rings include 5- or 6-memberednonaromatic heterocyclic rings optionally including one or two ringmembers selected from the group consisting of C(═O), SO or S(O)₂,optionally substituted. Examples of such R¹, R^(2a), R^(2b), R³, R⁴ andR⁵ carbon moieties include those illustrated as G-1 through G-35 inExhibit 2. Note that when the attachment point on these G groups isillustrated as floating, the G group can be attached to the remainder ofFormulae I and II through any available carbon or nitrogen of the Ggroup by replacement of a hydrogen atom. The optional substituents canbe attached to any available carbon or nitrogen by replacing a hydrogenatom (said substituents are not illustrated in Exhibit 2 since they areoptional substituents). Note that when G comprises a ring selected fromG-24 through G-31, G-34 and G-35, Q² may be selected from O, S, NH orsubstituted N.

It is noted that the carbon moieties of R¹, R^(2a), R^(2b), R³, R⁴ andR⁵ and the aryl and tertiary alkyl moieties of L may be optionallysubstituted. As noted above, the R¹, R^(2a), R^(2b), R³, R⁴ and R⁵carbon moieties may commonly comprise, among other groups, a U group ora G group further optionally substituted with from one to foursubstituents. The L aryl moiety may commonly comprise, among othergroups, a U group further optionally substituted with from one to foursubstituents. Thus the R¹, R^(2a), R^(2b), R³, R⁴ and R⁵ carbon moietiesmay comprise a U group or a G group selected from U-1 through U-88 orG-1 through G-35, and further substituted with additional substituentsincluding one to four U or G groups (which may be the same or different)with both the core U or G group and substituent U or G groups optionallyfurther substituted. The L moiety may comprise a U group selected fromU-1 through U-88 or a tertiary alkyl radical, and further substitutedwith additional substituents including one to four U or G groups (whichmay be the same or different) with both the core U group (or tertiaryalkyl radical) and the substituent U or G groups optionally furthersubstituted. Of particular note are L carbon moieties comprising a Ugroup optionally substituted with from one to three additionalsubstituents. For example, L can be U-11, in which an R^(v) attached tothe 1-nitrogen is the group U-41 as shown in Exhibit 3.

As generally defined herein, a “leaving group” denotes an atom or groupof atoms displaceable in a nucleophilic substitution reaction. Moreparticularly, “leaving group” refers to substituents X and Y, which aredisplaced in the reaction according to the method of the presentinvention. As is well known to those skilled in the art, a nucleophilicreaction leaving group carries the bonding electron pair with it as itis displaced. Accordingly the facility of leaving groups fordisplacement generally correlates with the stability of the leavinggroup species carrying the bonding electron pair. For this reason,strong leaving groups (e.g., Br, Cl, I and sulfonates such as OS(O)₂CH₃)give displaced species that can be regarded as the conjugate bases ofstrong acids. Because of its high electronegativity, fluoride (F) canalso be a strong leaving group from sp² carbon centers such as in acylfluorides.

According to the method of the present invention a compound of Formula Iis prepared by reacting a compound of Formula II with a compound ofFormula III as shown in Scheme 1.

-   -   wherein R¹, R^(2a), R^(2b), L, X and Y are as previously        defined.        Although the intermediate compound of Formula V can sometimes be        isolated, it is usually not, because it spontaneously cyclizes        to the corresponding compound of Formula I at room temperature.        The cyclization is sometimes slow at room temperature, but        proceeds at useful rates at elevated temperatures.

While the 5-oxo-pyrazoline product of Formula I is shown in Scheme 1 asa lactam, one skilled in the art recognizes that this is tautomeric withthe lactol of Formula Ib as shown in Scheme 2.

-   -   wherein R¹, R^(2a), R^(2b) and L are as previously, defined.        As these tautomers readily equilibrate, they are regarded as        chemically equivalent. Unless otherwise indicated, all        references to Formula I herein are to be construed to include        also Formula Ib.

Preferred for reason of ease of synthesis, better yield, higher purity,lower cost and/or product utility is the method of the present inventionwherein: L is preferably H, optionally substituted aryl or optionallysubstituted tertiary alkyl. More preferably, L is H or optionallysubstituted aryl. Even more preferably, L is optionally substitutedaryl. Most preferably, L is phenyl or pyridyl, each optionallysubstituted. R¹ is preferably C₁-C₁₆ alkyl, C₁-C₁₆ alkenyl or C₁-C₁₆alkynyl, each optionally substituted with one or more substituentsselected from halogen, C₁-C₄ alkoxy or phenyl. More preferably, R¹ isC₁-C₄ alkyl. Even more preferably, R¹ is C₁-C₂ alkyl. Most preferably,R¹ is methyl. Preferably, R^(2a) is H or an optionally substitutedcarbon moiety. More preferably, R^(2a) is H. Most preferably, R^(2a) andR^(2b) are each H. Preferably, each R³ is independently selected fromOR⁵ or an optionally substituted carbon moiety. More preferably, each R³is independently selected from an optionally substituted carbon moiety.Even more preferably, each R³ is independently selected from C₁-C₆ alkyloptionally substituted with one or more groups selected from halogen orC₁-C₄ alkoxy, or phenyl optionally substituted with 1-3 groups selectedfrom halogen, C₁-C₄ alkyl or C₁-C₄ alkoxy. Most preferably, each R³ isindependently selected from C₁-C₄ alkyl, phenyl or 4-methylphenyl.Preferably, each R⁵ is independently selected from C₁-C₆ alkyloptionally substituted with one or more groups selected from halogen orC₁-C₄ alkoxy. More preferably, each R⁵ is independently selected fromC₁-C₄ alkyl.

In the method of the present invention the leaving group Y of thestarting compound of Formula II is first displaced to give theintermediate compound of Formula V, from which the leaving group X isdisplaced to give the final product of Formula I. Strong leaving groupsare generally suitable for X and Y in the present method. Preferablyleaving groups are selected for X and Y in view of their relativesusceptibility to displacement so that leaving group Y is displacedbefore leaving group X. However, as nucleophilic substitution isinherently more rapid on acyl centers compared to the 2-position ofesters, most combinations of strong leaving groups work well for X and Yin the present method. X is preferably Cl, Br, I or a sulfonate (e.g.,OS(O)₂CH₃, OS(O)₂CF₃, OS(O)₂Ph, OS(O)₂Ph-4-Me). More preferably, X isCl, Br or I. Even more preferably, X is Cl or Br. Most preferably, X isBr. Y is preferably F, Cl, Br or I. More preferably, Y is Cl or Br. Mostpreferably, Y is Cl. The combination of X being Br and Y being Cl isnotable for rapid condensation according to the method of the presentinvention to give a compound of Formula I in high yield andregioselectivity.

The reaction is conducted in the presence of a suitable acid scavenger.Suitable acid scavengers for the method of the present invention includebases and also chemical compounds not typically considered bases butnevertheless capable of reacting with and consuming strong acids such ashydrogen chloride and hydrogen bromide. Nonbasic acid scavengers includeepoxides such as propylene oxide and olefins such as 2-methylpropene.Bases include ionic bases and nonionic bases. Nonionic bases includeorganic amines. Organic bases providing best results include amines thatare only moderately basic and nucleophilic, e.g., N,N-diethylaniline.Useful ionic bases include fluorides, oxides, hydroxides, carbonates,carboxylates and phosphates of alkali and alkaline earth metal elements.Examples include NaF, MgO, CaO, LiHCO₃, Li₂CO₃, LiOH, NaOAc, NaHCO₃,Na₂CO₃, Na₂HPO₄, Na₃PO₄, KHCO₃, K₂CO₃, K₂HPO₄ and K₃PO₄. Givingparticularly good results are inorganic carbonate and phosphate basescomprising alkali metal elements (e.g., LiHCO₃, Li₂CO₃, Li₂HPO₄, Li₃PO₄,NaHCO₃, Na₂CO₃, Na₂HPO₄ and Ma₃PO₄). Of these, preferred for their lowcost as well as excellent results are NaHCO₃, Na₂CO₃, Na₂HPO₄ andNa₃PO₄. Particularly preferred is NaHCO₃ and Na₃PO₄. Most preferred isNaHCO₃. Preferably at least two equivalents of acid scavenger isemployed in the method of the present invention. Typically about 2 to2.5 equivalents of acid scavenger is used. For the reaction ofrelatively acidic hydrazines of Formula III wherein, for example, L is—S(O)₂R³ it may be advantagous to add first an acid scavenger that isnot a strong base to avoid deprotonating the hydrazine moiety of FormulaIII during the formation of the intermediate of Formula V and then add astrong base to deprotonate the hydrazine moiety of Formula V toaccelerate the condensation to give the final product of Formula I.

Suitable solvents include polar aprotic solvents such asN,N-dimethylformamide, methyl sulfoxide, ethyl acetate, dichloromethane,acetonitrile and the like. Nitrile solvents such as acetonitrile,proprionitrile and butyronitrile often provide optimal yields andproduct purities. Particularly preferred for its low cost and excellentutility as solvent for the method of this invention is acetonitrile.

The method of the present invention can be conducted over a widetemperature range, but is typically conducted at temperatures betweenabout −10 and 80° C. While the intermediate compound of Formula V can beformed at 80° C. or higher, the best yields and purities are oftenachieved by forming it at lower temperature, such as between about 0° C.and ambient temperature (e.g., about 15 to 25° C.). Typically during theaddition of reactants the reaction mixture is cooled to a temperature of−5 to 5° C., most conveniently about 0° C. After the reactants have beencombined, the temperature is typically increased to near ambienttemperature. To then increase the rate of cyclization of the compound ofFormula V to the compound of Formula I, a temperature in the range ofabout 30 to 80° C. is usually employed, more typically about 30 to 60°C., and most typically about 40° C. The product of Formula I can beisolated by the usual methods well known to those skilled in the artsuch as evaporation of solvent, chromatography and crystallization.Addition of an acid with a pK_(a) in the range of 2 to 5 can bufferexcess base and prevent saponification and degradation of the product ofFormula I during isolation steps involving water and heat (such asremoval of solvent by distillation). Acetic acid works well for thispurpose. Also, addition of such acids as acetic acid to concentratedsolutions of certain products of Formula I can promote theircrystallization.

Preferred methods of this invention include the method wherein thestarting compound of Formula II is Formula IIa, the starting compound ofFormula III is Formula IIIa and the product compound of Formula I isFormula Ia as shown in Scheme 3 below.

-   -   wherein R¹ is as defined for Formulae I and II;    -   X and Y are as defined for Formula II;    -   each R⁹ is independently C₁-C₄ alkyl, C₂-C₄ alkenyl, C₂-C₄        alkynyl, C₃-C₆ cycloalkyl, C₁-C₄ haloalkyl, C₂-C₄ haloalkenyl,        C₂-C₄ haloalkynyl, C₃-C₆ halocycloalkyl, halogen, CN, NO₂, C₁-C₄        alkoxy, C₁-C₄ haloalkoxy, C₁-C₄ alkylthio, C₁-C₄ alkylsulfinyl,        C₁-C₄ alkylsulfonyl, C₁-C₄ alkylamino, C₂-C₈ dialkylamino, C₃-C₆        cycloalkylamino, (C₁-C₄ alkyl)(C₃-C₆ cycloalkyl)amino, C₂-C₄        alkylcarbonyl, C₂-C₆ alkoxycarbonyl, C₂-C₆ alkylaminocarbonyl,        C₃-C₈ dialkylaminocarbonyl or C₃-C₆ trialkylsilyl;    -   Z is N or CR¹⁰;    -   R¹⁰ is H or R⁹; and    -   n is an integer from 0 to 3.        One skilled in the art will recognize that Formula Ia is a        subgenus of Formula I, Formula IIa is subgenus of Formula II,        Formula IIIa is a subgenus of Formula III, and Formula Va is a        subgenus of Formula V.

While a wide range of optionally substituted carbon moieties as alreadydescribed are useful as R¹ in esters of Formula Ia for the method ofScheme 3, commonly R¹ is a radical containing up to 18 carbon atoms andselected from alkyl, alkenyl and alkynyl; and benzyl and phenyl, eachoptionally substituted with alkyl and halogen. Preferably R¹ is C₁-C₄alkyl, more preferably R¹ is C₁-C₂ alkyl, and most preferably R¹ ismethyl. Preferably X is Cl or Br, and more preferably X is Br.Preferably Y is Cl. Of note is the method shown in Scheme 3 wherein Z isN, n is 1 and R⁹ is Cl or Br and is located at the 3-position.

As shown in Scheme 4, compounds of Formula II can be prepared bytreating the corresponding carboxylic acids of Formula VI with theappropriate reagents to convert the hydroxy radical of the carboxylicacid function into a leaving group.

-   -   wherein R¹, R^(2a), R^(2b), X and Y are as previously defined.

For example, a compound of Formula IIb (i.e. Formula II wherein Y is Cl)can be prepared by contacting a corresponding carboxylic acid of FormulaVI with a reagent for converting carboxylic acids to acyl chlorides,such as thionyl chloride (S(O)Cl₂) as shown in Scheme 5.

-   -   wherein R¹, R^(2a), R^(2b) and X are as previously defined.        The reaction of the carboxylic acid of Formula VI with thionyl        chloride is typically conducted in the presence of a moderately        polar aprotic solvent such as dichloromethane,        1,2-dichloroethane, benzene, chlorobenzene or toluene. The        reaction can be catalyzed by addition of N,N-dimethylformamide.        Typically the reaction temperature is in the range of about 30        to 80° C. When dichloromethane-is used as solvent, the reaction        is conveniently conducted at about its boiling point of 40° C.        Rapid removal of hydrogen chloride generated by the reaction is        desirable and can be facilitated by boiling the solvent to limit        the solubility of the hydrogen chloride. Because of its moderate        boiling point, dichloromethane is preferred as a solvent.

Because of compounds of Formula VI can be easily and inexpensivelyconverted to compounds of Formula II wherein Y is Cl (i.e. Formula IIb),Y being Cl is preferred for the method of the present invention.However, other leaving groups are also useful as Y in the presentmethod. Compounds of Formula II wherein Y is a leaving group other thanCl can be prepared either directly from the corresponding compounds ofFormula VI or from the compounds of Formula IIb by methods well known tothose skilled in the art (see, for example, H. W. Johnson & D. E.Bublitz, J. Am. Chem. Soc. 1958, 80, 3150-3152 (VI to II (Y is Br)); G.Oláh et al., Chem. Ber. 1956, 89, 862-864 (IIb to II (Y is F)); R. N.Haszeldine, J. Chem. Soc. 1951, 584587 (IIb to II (Y is I))).

As discussed above, acyl halide compounds of Formula II are easilyprepared from the corresponding carboxylic acids of Formula VI bycontacting with thionyl chloride (for Y is Cl) or other reagents for Ybeing another halide, or by contacting a compound of Formula II whereinY is Cl with the appropriate reagent to convert Y to another halogen.Even though acyl halide compounds of Formula II are easily prepared,they are less simply isolated in 100% concentration, because they aretypically not crystalline and at reduced pressures commonly availablefor chemical manufacturing their boiling points are typically higherthan their decomposition temperatures, thereby precluding distillingthem. Although solvents can be removed from acyl halide compounds ofFormula II by such methods as evaporation or distillation of the solventat reduced pressure, typically sufficient solvent is entrained to causethe concentration of the Formula II compound to remain below 100%.However, the solvents used to prepare the compounds of Formula II aregenerally compatible with the method of the present invention, andtherefore the method of the present invention works well starting withcompositions of compounds of Formula II wherein the concentration ofFormula II compound is less than 100%. Therefore a composition ofFormula II compound useful for the method of the present inventiontypically also comprises a solvent, particularly a solvent used toprepare the Formula II compound. Typical solvents includedichloromethane, 1,2-dichloroethane, benzene, chlorobenzene or toluene.Typically said composition comprises about 20 to 99% of Formula IIcompound on a weight basis. Preferably said composition comprises about40 to 99 weight % of Formula II compound. More preferably saidcomposition comprises about 50 to 99 weight % of Formula II compound.Also preferably said composition comprises at least about 80% of FormulaII compound based on the sum of the weight of the Formula II compound(including all stereoisomers) and the weights of regioisomers of theFormula II compound in the composition. (For this calculation, theweight of Formula II compound (including all stereoisomers) is dividedby the sum of the weight of the Formula II compound (including allstereoisomers) and the weights of regioisomers of the Formula IIcompound, and then the resulting division quotient is multiplied by100%. The regioisomers of Formula II involve, for example, interchangingthe placement of X and R^(2a) or R^(2b).) More preferably saidcomposition comprises at least about 90% of the Formula II compoundbased on the total weight of the Formula II compound and itsregioisomers in the composition (i.e. the aforementioned sum ofweights). Most preferably said composition comprises at least about 94%of Formula II compound based on the total weight of the Formula IIcompound and its regioisomers in the composition. Preferred is acomposition comprising a compound of Formula II wherein Y is Cl and X isCl, Br or I, preferably Cl or Br, and more preferably Br. Of note is acomposition, including said preferred composition, comprising a compoundof Formula II wherein when R^(2a) and R^(2b) are each H, and X and Y areeach Cl then R¹ is other than benzyl and when R^(2a) and R^(2b) are eachphenyl, and X and Y are each Cl, then R¹ is other than methyl or ethyl.Particularly preferred is a composition comprising the compound ofFormula II wherein R^(2a) and R^(2b) are each H, X is Br, Y is Cl and R¹is methyl. Also particularly preferred is a composition comprising thecompound of Formula II wherein R^(2a) and R^(2b) are each H, X is Br, Yis Cl and R¹ is ethyl. This invention also pertains to the compounds ofFormula II comprised by said compositions, including preferredcompositions and compositions of note. Compounds of Formula VI can beprepared by a variety of chemical routes disclosed in the literature.For example, the compound of Formula VI wherein R^(2a) and R^(2b) are H,X is Br and R¹ is ethyl can be prepared as described by U. Aeberhard etal., Helv. Chim. Acta 1983, 66, 2740-2759. The compound of Formula VIwherein R^(2a) and R^(2b) are H, X is Cl and R¹ is benzyl can beprepared as described by J. E. Baldwin et al., Tetrahedron 1985, 41,241. Compounds of Formula VI wherein R^(2a) and R^(2b) are H and X isOS(O)₂Me, and R¹ is ethyl, ethyl, isopropyl or benzyl can be prepared asdescribed by S. C. Arnold & R. W. Lenz, Makromol. Chem. Macromol. Symp.1986, 6, 285-303 and K. Fujishiro et al., Liquid Crystals 1992, 12 (3),417-429. One skilled in the art appreciates that these example routescan be generalized. Of special interest is the compound of Formula VIwherein R^(2a) and R^(2b) are H, X is Br and R¹ is methyl, because itscrystalline nature facilitates purification. Therefore the presentinvention also relates to a crystalline composition (e.g., crystals)comprising at least about 90% by weight, preferably at least about 95%by weight, of the compound of Formula VI wherein R^(2a) and R^(2b) areH, X is Br and RI is methyl. Impurities in said crystalline compositioncan for example comprise regioisomers of the Formula VI compound and/orthe solvent of crystallization entrained in the crystal lattice.

Compounds of Formula III can be prepared by a wide variety of methodsreported in the literature, for example, see G. H. Coleman in Org. Syn.Coll. Vol. I, 1941, 442-445 (L is aryl); O. Diels, Chem. Ber. 1914, 47,2183-2195 (L is —C(O)R³); L. F. Audrieth & L. H. Diamond, J. Am. Chem.Soc. 1954, 76, 4869-4871 (L is tertiary alkyl); L. Friedman et al. inOrg. Syn. 1960, 40, 93-95 (L is S(O)₂R³); and V. S. Sauro & M. S.Workentin, Can. J. Chem. 2002, 80, 250-262 (L is P(O)(R3)₂). It isbelieved that one skilled in the art using the preceding description canutilize the present invention to its fullest extent. The followingExample is, therefore, to be construed as merely illustrative, and notlimiting of the disclosure in any way whatsoever. Steps in the followingExample illustrate a procedure for each step in an overall synthetictransformation, and the starting material for each step may not havenecessarily been prepared by a particular preparative run whoseprocedure is described in other Examples or Steps. Percentages are byweight except for chromatographic solvent mixtures or where otherwiseindicated. Parts and percentages for chromatographic solvent mixturesare by volume unless otherwise indicated. ¹H NMR spectra are reported inppm downfield from tetramethylsilane; “s” means singlet, “d” meansdoublet, “t” means triplet, “q” means quartet, “m” means multiplet, “dd”means doublet of doublets, “dt” means doublet of triplets, and “br s”means broad singlet. “ABX” refers to a ¹H NMR three-proton spin systemin which two protons “A” and “B” have a chemical shift difference thatis relatively small compared to their spin-spin coupling and the thirdproton “X”) has a chemical shift with a relatively large differencecompared to the spin-spin coupling with protons “A” and “B”.

EXAMPLE 1 Preparation of methyl2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate (Formula Iwherein R¹ is methyl, R^(2a) and R^(2b) are H and L is3-chloro-2-pyridinyl)

Step A: Preparation of 1-methyl hydrogen bromobutanedioate

Methyl hydrogen (2Z)-2-butendioate (also known as the monomethyl esterof maleic acid) (50 g, 0.385 mol) was added dropwise to a solution ofhydrogen bromide in acetic acid 141.43 g, 33%, 0.577 mol) at 0° C. over1 h. The reaction mixture was stored at about 5° C. overnight. Thesolvent was then removed under reduced pressure. Toluene (100 mL) wasadded, and the mixture was evaporated under reduced pressure. Theprocess was repeated three times using more toluene (3×100 mL). Thentoluene (50 mL) was added, and the mixture was cooled to −2° C. Hexanes(50 mL) was added dropwise to the mixture. When the addition wascomplete the mixture was stirred about 30 minutes while the productcrystallized. The product was then isolated by filtration and dried invacuo to provide the title compound as a white solid (63.37 g, 81.8%yield). A sample recrystallized from toluene/hexanes melted at 38-40° C.

IR (nujol): 1742, 1713, 1444, 1370, 1326, 1223, 1182, 1148, 1098, 996,967, 909, 852 cm⁻¹.

¹H NMR (CDCl₃) δ 4.57 (X of ABX pattern, J=6.1, 8.9 Hz, 1H), 3.81 (s,3H), 3.35 (½ of AB in ABX pattern, J=8.8, 17.7 Hz, 1H), 3.05 (½ of AB inABX pattern, J=6.1, 17.8 Hz, 1H).

Step B: Preparation of methyl 2-bromo-4-chloro4-oxobutanoate

Thionyl chloride (6.54 g, 54.9 mmol) in dichloromethane (7 mL) was addeddropwise over 30 minutes to a mixture of 1-methyl hydrogenbromobutanedioate (i.e. the product of Step A) (10 g, 47.4 mmol) andN,N-dimethylformamide (5 drops) in dichloromethane (20 mL) heated atreflux. The mixture was heated at reflux for an additional 60 minutesand then allowed to cool to room temperature. The solvent was removedunder reduced pressure to leave the title product as an oil (11 g, about100% yield).

IR (nujol): 3006, 2956, 1794, 1743, 1438, 1392, 1363, 1299, 1241, 1153,1081, 977, 846, 832 cm⁻¹.

¹H NMR (CDCl₃) δ 4.56 (X of ABX pattern, J=5.8, 8.5 Hz, 1H), 3.87-3.78(m, 4E), 3.53 (½ of AB in ABX pattern, J=6, 18.5 Hz, 1H).

Step C: Preparation of methyl2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidine-carboxylate

The crude product of Step B (i.e. methyl 2-bromo4-chloro4-oxobutanoate)(11.00 g, ˜47.4 mmol) in acetonitrile (25 mL) was added over 65 minutesto a mixture of 3-chloro-2(1H)-pyridinone hydrazone (alternatively named(3-chloro-pyridin-2-yl)-hydrazine) (6.55 g, 45.6 mmol) and sodiumbicarbonate (9.23 g, 0.110 mol) in acetonitrile (60 mL) at 0° C. Themixture was then allowed to warm to room temperature and was stirred for3 h. The mixture was then warmed and maintained at 38° C. for 8 h. Thenthe mixture was allowed to cool, and the solvent was removed byevaporation under reduced pressure. Water (25 mL) was added, and aceticacid (about 1.9 mL) was added until the slurry had a pH of about 5.After 2 h, the product was isolated by filtration, rinsed with water (10mL) and dried in vacuo to provide the title compound as a pale yellowsolid (11 g, 89.8% yield). A sample recrystallized from ethanol meltedat 147-148° C.

IR (nujol): 1756, 1690, 1581, 1429, 1295, 1202, 1183, 1165, 1125, 1079,1032, 982, 966, 850, 813 cm⁻¹.

¹H NMR (DMSO-d₆) δ 10.16 (s, 1H), 8.27 (dd, J=1.4, 4.6 Hz, 1H), 7.93(dd, J=1.6, 7.8 Hz, 1H), 7.19 (dd, J=4.6, 7.8 Hz, 1H), 4.87 (X of ABXpattern, J=1.6, 9.6 Hz, 1H), 3.73 (s, 3H), 2.90 (½ of AB in ABX pattern,J=9.7, 16.7 Hz, 1H), 2.38 (½ of AB in ABX pattern, J=1.6, 16.9 Hz, 1H).

By the procedures described herein together with methods known in theart, the compounds of Formulae II and III can be converted to compoundsof Formula I as illustrated for Formulae Ia, IIa and IIIa in Table 1 andmore generally for Formulae I, II and III in Table 2. The followingabbreviations are used in the Tables: t is tertiary, s is secondary, nis normal, i is iso, Me is methyl, Et is ethyl, Pr is propyl, i-Pr isisopropyl, t-Bu is tertiary butyl, Ph is phenyl and Bn is benzyl(—CH₂Ph). TABLE 1

X is Br; Y is Cl R¹ is Me R¹ is Et R¹ is t-Bu R¹ is Bn (R⁹)_(n) Z(R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z(R⁹)_(n) Z 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl 3-Cl N 3-ClCCl 3-Br N 3-Br CCI 3-Br N 3-Br CCl 3-Br N 3-Br CCl 3-Br N 3-Br CCl 3-ClCH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Br CH3-Br CBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBr X is Cl; Yis Cl R¹ is Me R¹ is Et R¹ is t-Bu R¹ is Bn (R⁹)_(n) Z (R⁹)_(n) Z(R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z 3-Cl N3-Cl CCl 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl 3-Br N 3-Br CCI3-Br N 3-Br CCl 3-Br N 3-Br CCl 3-Br N 3-Br CCl 3-Cl CH 3-Cl CBr 3-Cl CH3-Cl CBr 3-Cl CH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Br CH 3-Br CBr 3-Br CH 3-BrCBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBr X is OS(O)₂Me; Y is Cl R¹ is Me R¹is Et R¹ is t-Bu R¹ is Bn (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z(R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z 3-Cl N 3-Cl CCl 3-Cl N 3-ClCCl 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl 3-Br N 3-Br CCI 3-Br N 3-Br CCl 3-BrN 3-Br CCl 3-Br N 3-Br CCl 3-Cl CH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Cl CH3-Cl CBr 3-Cl CH 3-Cl CBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBr 3-Br CH 3-BrCBr 3-Br CH 3-Br CBr X is OS(O)2Ph; Y is Cl R¹ is Me R¹ is Et R¹ is t-BuR¹ is Bn (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n) Z (R⁹)_(n)Z (R⁹)_(n) Z (R⁹)_(n) Z 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl 3-Cl N 3-Cl CCl3-Cl N 3-Cl CCl 3-Br N 3-Br CCI 3-Br N 3-Br CCl 3-Br N 3-Br CCl 3-Br N3-Br CCl 3-Cl CH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Cl CH 3-Cl CBr 3-Cl CH 3-ClCBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBr 3-Br CH 3-Br CBrX is Br; Y is Cl (R⁹)_(n) R¹ Z (R⁹)_(n) R¹ Z (R⁹)_(n) R¹ Z (R⁹)_(n) R¹ Z5-Cl Me CH 3-OEt Me N 4-I Me CH 5-CF₂H Me CH 4-n-Bu Et N 2-OCF₃ Et N3-CN Et CH 6-CH₃ Et N 5-NMe₂ n-Pr CH 3-cyclo-Pr n-Pr CH 3-NO₂ n-Pr CH3-CH₂CF₃ n-Pr CH 3-OCH₂F i-Pr N H i-Pr N 3-S(O)₂CH₃ i-Pr CH 6-cyclohexyli-Pr CH 4-OCH₃ n-Bu CH 4-F n-Bu CCl 4-SCH₃ n-Bu CH 4-CH₂CH═CH₂ n-Bu CH3-Me s-Bu N 4-Me i-Bu CH 3-Br Bn N 3-CF₃ t-Bu N (R⁹)_(n) is 3-Br; Z isCBr R¹ is Me R¹ is Et R¹ is n-Bu X Y X Y X Y X Y X Y X Y Cl Br I Cl ClBr I Cl Cl Br I Cl Br Br OS(O)₂Ph-4-Me Cl Br Br OS(O)₂Ph-4-Me Cl Br BrOS(O)₂Ph-4-Me Cl Br I OS(O)₂CF₃ Cl Br I OS(O)₂CF₃ Cl Br I OS(O)₂CF₃ ClBr F OS(O)₂CH₂CH₃ Cl Br F OS(O)₂CH₂CH₃ Cl Br F OS(O)₂CH₂CH₃ Cl (R⁹)_(n)is 3-Cl; Z is N R¹ is Me R¹ is Et R¹ is n-Bu X Y X Y X Y X Y X Y X Y ClBr I Cl Cl Br I Cl Cl Br I Cl Br Br OS(O)₂Ph-4-Me Cl Br Br OS(O)₂Ph-4-MeCl Br Br OS(O)₂Ph-4-Me Cl Br I OS(O)₂CF₃ Cl Br I OS(O)₂CF₃ Cl Br IOS(O)₂CF₃ Cl Br F OS(O)₂CH₂CH₃ Cl Br F OS(O)₂CH₂CH₃ Cl Br F OS(O)₂CH₂CH₃Cl

TABLE 2

R¹ is Me, X is Br, Y is Cl R^(2a) R^(2b) L R^(2a) R^(2b) L H H Ph-4-Me HH —P(O)(OMe)₂ Me H Ph H H —P(O)(OMe)Ph OMe H Ph H H —P(O)Et₂ Me MePh-2-Cl H H —C(CH₃)₂(CH₂)₂CH₃ H H 3-thienyl H H —C(CH₃)₂CF₃ H H t-Bu H H—C(CH₃)₂CH₂OCH₃ H H —C(O)Ph Me H Ph-3-OMe H H —C(O)OMe Ph Ph Ph H H—C(O)N(Me)Et CH₂CF₃ H 2-napthyl H H —S(O)₂Me O-allyl H Ph H H—S(O)₂Ph-4-Me Me CH₂OCH₃ Ph-2,4-di-Me H H Ph-Ph-4-Me —(CH₂)₄— Ph H2-thienyl Ph-3-OMe —(CH₂)₂O(CH₂)₂— Ph-4-i-Pr H H Ph R¹ is Et, X is Br, Yis Cl R^(2a) R^(2b) L R^(2a) R^(2b) L H H Ph-3-Cl H H —P(O)(OEt)₂ Et HPh H H —P(O)(OEt)Ph-4-Me OEt H Ph H H —P(O)Me₂ Me n-Pr Ph-2-Me H H—C(CH₃)₂(CH₂)₄CH₃ H H 3-thienyl-2-Me H H —C(CH₃)₂CH₂CF₃ Me H t-Bu H H—C(CH₂CH₃)₂CH₃ H H —C(O)Ph-4-Cl Et H Ph-3-OMe H H —C(O)OCH₂CH₂OCH₃ Ph PhPh-4-OEt H H —C(O)N(Me)₂ H H 1-napthyl H H —S(O)₂Me O-allyl H Ph-4-Me HH —S(O)₂Ph-3-Br Me CH₂OCH₃ Ph-2,4-di-Cl H H Ph-Ph-4-Cl —(CH₂)₄— Ph-3-F H2-thienyl Ph-4-OMe —(CH₂)₂O(CH₂)₂— Ph-4-CH(CH₃)₂ H H Ph

Among the compounds preparable according to the method of the presentinvention, compounds of Formula Ia are particularly useful for preparingcompounds of Formula IV

wherein Z, R³ and n are defined as above; X¹ is halogen; R⁶ is CH₃, F,Cl or Br; R⁷ is F, Cl, Br, I, CN or CF₃; R^(8a) is H or C₁-C₄ alkyl; andR^(8b) is H or CH₃. Preferably Z is N, n is 1, and R³ is Cl or Br and isat the 3-position.

Compounds of Formula IV are useful as insecticides, as described, forexample, in PCT Publication No. WO 01/70671, published Sep. 27, 2001,PCT Publication No. WO 03/015519, published Feb. 27, 2003, and PCTPublication No. WO 03/015518, published Feb. 27, 2003, as well as inU.S. Patent Application 60/323,941, filed Sep. 21, 2001, the disclosureof which was substantively published on Mar. 27, 2003 in PCT PublicationNo. WO 03/024222. The preparation of compounds of Formula 9 and FormulaIV is described in U.S. Patent Application 60/446451, filed Feb. 11,2003 and U.S. Patent Application 60/446438, filed Feb. 11, 2003, andhereby incorporated herein in their entirety by reference; as well as inPCT Publication No. WO 03/016283, published Feb. 27, 2003.

Compounds of Formula IV can be prepared from corresponding compounds ofFormula Ia by the processes outlined in Schemes 6-11.

As illustrated in Scheme 6, a compound of Formula Ia is treated with ahalogenating reagent, usually in the presence of a solvent to providethe corresponding halo compound of Formula 6.

-   -   wherein R¹, R⁹, Z and n are as previously defined, and X¹ is        halogen.        Halogenating reagents that can be used include phosphorus        oxyhalides, phosphorus trihalides, phosphorus pentahalides,        thionyl chloride, dihalotrialkylphosphoranes,        dihalodiphenylphosphoranes, oxalyl chloride, phosgene, sulfur        tetrafluoride and (diethylamino)sulfur trifluoride. Preferred        are phosphorus oxyhalides and phosphorus pentahalides. To obtain        complete conversion, at least 0.33 equivalents of phosphorus        oxyhalide versus the compound of Formula Ia (i.e. the mole ratio        of phosphorus oxyhalide to Formula Ia is at least 0.33) should        be used, preferably between about 0.33 and 1.2 equivalents. To        obtain complete conversion, at least 0.20 equivalents of        phosphorus pentahalide versus the compound of Formula Ia should        be used, preferably between about 0.20 and 1.0 equivalents.        Typical solvents for this halogenation include halogenated        alkanes, such as dichloromethane, chloroform, chlorobutane and        the like, aromatic solvents, such as benzene, xylene,        chlorobenzene and the like, ethers, such as tetrahydrofuran,        p-dioxane, diethyl ether, and the like, and polar aprotic        solvents such as acetonitrile, N,N-dimethylformamide, and the        like. Optionally, an organic base, such as triethylamine,        pyridine, N,N-dimethylaniline or the like, can be added.        Addition of a catalyst, such as N,N-dimethylformamide, is also        an option. Preferred is the process in which the solvent is        acetonitrile and a base is absent. Typically, neither a base nor        a catalyst is required when acetonitrile solvent is used. The        preferred process is conducted by mixing the compound of Formula        Ia in acetonitrile. The halogenating reagent is then added over        a convenient time, and the mixture is then held at the desired        temperature until the reaction is complete. The reaction        temperature is typically between about 20° C. and the boiling        point of acetonitrile, and the reaction time is typically less        than 2 hours. The reaction mass is then neutralized with an        inorganic base, such as sodium bicarbonate, sodium hydroxide and        the like, or an organic base, such as sodium acetate. The        desired product, a compound of Formula 6, can be isolated by        methods known to those skilled in the art, including extraction,        crystallization and distillation.

Alternatively as shown in Scheme 7, compounds of Formula 6 wherein X¹ ishalogen such as Br or Cl can be prepared by treating the correspondingcompounds of Formula 6a wherein x2 is a different halogen (e.g., Cl formaking Formula 6 wherein X¹ is Br) or a sulfonate group such asmethanesulfonate, benzenesulfonate or p-toluenesulfonate with hydrogenbromide or hydrogen chloride, respectively.

-   -   wherein R¹, R⁹ and n are as previously defined for Formula Ia.        By this method the X2 halogen or sulfonate substituent on the        Formula 6a starting compound is replaced with Br or Cl from        hydrogen bromide or hydrogen chloride, respectively. The        reaction is conducted in a suitable solvent such as        dibromomethane, dichloromethane, acetic acid, ethyl acetate or        acetonitrile. The reaction can be conducted at or near        atmospheric pressure or above atmospheric pressure in a pressure        vessel. The hydrogen halide starting material can be added in        the form of a gas to the reaction mixture containing the Formula        6a starting compound and solvent. When X² in the starting        compound of Formula 6a is a halogen such as Cl, the reaction is        preferably conducted in such a way that the hydrogen halide        generated from the reaction is removed by sparging or other        suitable means. Alternatively, the hydrogen halide starting        material can be first dissolved in an inert solvent in which it        is highly soluble (such as acetic acid) before contacting with        the starting compound of Formula 6a either neat or in solution.        Also when X² in the starting compound of Formula 6a is a halogen        such as Cl, substantially more than one equivalent of hydrogen        halide starting material (e.g., 4 to 10 equivalents) is        typically needed depending upon the level of conversion desired.        One equivalent of hydrogen halide starting material can provide        high conversion when X² in the starting compound of Formula 6a        is a sulfonate group, but when the starting compound of Formula        6a comprises at least one basic function (e.g., a        nitrogen-containing heterocycle), more than one equivalent of        hydrogen halide starting material is typically needed. The        reaction can be conducted between about 0 and 100° C., most        conveniently near ambient temperature (e.g., about 10 to 40°        C.), and more preferably between about 20 and 30° C. Addition of        a Lewis acid catalyst (such as aluminum tribromide for preparing        Formula 6 wherein X¹ is Br) can facilitate the reaction. The        product of Formula 6 is isolated by the usual methods known to        those skilled in the art, including extraction, distillation and        crystallization.

Starting compounds of Formula 6a wherein X² is Cl or Br are also ofFormula 6 and can be prepared from corresponding compounds of Formula Iaas already described for Scheme 6. Starting compounds of Formula 6awherein X² is a sulfonate group can likewise be prepared fromcorresponding compounds of Formula Ia by standard methods such astreatment with a sulfonyl chloride (e.g., methanesulfonyl chloride,benzenesulfonyl chloride or p-toluenesulfonyl chloride) and base in asuitable solvent. Suitable solvents include dichloromethane,tetrahydrofuran, acetonitrile and the like. Suitable bases includetertiary amines (e.g., triethylamine, N,N-diisopropylethylamine) andionic bases such as potassium carbonate and the like. A tertiary amineis preferred as the base. At least one of equivalent (preferably a smallexcess, e.g., 5-10%) of the sulfonyl chloride compound and the baserelative to the compound Formula Ia is generally used to give completeconversion. The reaction is typically conducted at a temperature betweenabout −50° C. and the boiling point of the solvent, more commonlybetween about 0° C. and ambient temperature (i.e. about 15 to 30° C.).The reaction is typically complete within a couple hours to severaldays; the progress of the reaction can by monitored by such techniquesknown to those skilled in the art as thin layer chromatography andanalysis of the ¹H NMR spectrum. The reaction mixture is then worked up,such as by washing with water, drying the organic phase and evaporatingthe solvent. The desired product, a compound of Formula 6a wherein X² isa sulfonate group, can be isolated by methods known to those skilled inthe art, including extraction, crystallization and distillation. Asillustrated in Scheme 8, a compound of Formula 6 is then treated with anoxidizing agent optionally in the presence of acid.

-   -   wherein R¹, R⁹, Z, X¹ and n are as previously defined for        Formula 6 in Scheme 6.        A compound of Formula 6 wherein R¹ is C₁-C₄ alkyl is preferred        as starting material for this step. The oxidizing agent can be        hydrogen peroxide, organic peroxides, potassium persulfate,        sodium persulfate, ammonium persulfate, potassium monopersulfate        (e.g., Oxone®) or potassium permanganate. To obtain complete        conversion, at least one equivalent of oxidizing agent versus        the compound of Formula 6 should be used, preferably from about        one to two equivalents. This oxidation is typically carried out        in the presence of a solvent. The solvent can be an ether, such        as tetrahydrofuran, p-dioxane and the like, an organic ester,        such as ethyl acetate, dimethyl carbonate and the like, or a        polar aprotic organic such as N,N-dimethylformamide,        acetonitrile and the like. Acids suitable for use in the        oxidation step include inorganic acids, such as sulfuric acid,        phosphoric acid and the like, and organic acids, such as acetic        acid, benzoic acid and the like. The acid, when used, should be        used in greater than 0.1 equivalents versus the compound of        Formula 6. To obtain complete conversion, one to five        equivalents of acid can be used. For the compounds of Formula 6        wherein Z is CR¹⁰, the preferred oxidant is hydrogen peroxide        and the oxidation is preferably carried out in the absence of        acid. For the compounds of Formula 6 wherein Z is N, the        preferred oxidant is potassium persulfate and the oxidation is        preferably carried out in the presence of sulfuric acid. The        reaction can be carried out by mixing the compound of Formula 6        in the desired solvent and, if used, the acid. The oxidant can        then be added at a convenient rate. The reaction temperature is        typically varied from as low as about 0° C. up to the boiling        point of the solvent in order to obtain a reasonable reaction        time to complete the reaction, preferably less than 8 hours. The        desired product, a compound of Formula 7 can be isolated by        methods known to those skilled in the art, including extraction,        chromatography, crystallization and distillation.

Carboxylic acid compounds of Formula 7 wherein R¹ is H can be preparedby hydrolysis from corresponding ester compounds of Formula 7 wherein,for example, R¹ is C₁-C₄ alkyl. Carboxylic ester compounds can beconverted to carboxylic acid compounds by numerous methods includingnucleophilic cleavage under anhydrous conditions or hydrolytic methodsinvolving the use of either acids or bases (see T. W. Greene and P. G.M. Wuts, Protective Groups in Organic Synthesis, 2nd ed., John Wiley &Sons, Inc., New York, 1991, pp. 224-269 for a review of methods). Forcompounds of Formula 7, base-catalyzed hydrolytic methods are preferred.Suitable bases include alkali metal (such as lithium, sodium orpotassium) hydroxides. For example, the ester can be dissolved in amixture of water and an alcohol such as ethanol. Upon treatment withsodium hydroxide or potassium hydroxide, the ester is saponified toprovide the sodium or potassium salt of the carboxylic acid.Acidification with a strong acid, such as hydrochloric acid or sulfuricacid, yields the carboxylic acid of Formula 7 wherein R¹ is H. Thecarboxylic acid can be isolated by methods known to those skilled in theart, including extraction, distillation and crystallization.

Coupling of a pyrazolecarboxylic acid of Formula 7 wherein R¹ is H withan anthranilic acid of Formula 8 provides the benzoxazinone of Formula9. In Scheme 9, a benzoxazinone of Formula 9 is prepared directly viasequential addition of methanesulfonyl chloride in the presence of atertiary amine such as triethylamine or pyridine to a pyrazolecarboxylicacid of Formula 7 wherein RI is H, followed by the addition of ananthranilic acid of Formula 8, followed by a second addition of tertiaryamine and methanesulfonyl chloride.

-   -   wherein R⁶, R⁷, R⁹, X¹, Z and n are as defined for Formula IV.        This procedure generally affords good yields of the        benzoxazinone.

Scheme 10 depicts an alternate preparation for benzoxazinones of Formula9 involving coupling of a pyrazole acid chloride of Formula 11 with anisatoic anhydride of Formula 10 to provide the Formula 9 benzoxazinonedirectly.

-   -   wherein R⁶, R⁷, R⁹, X¹, Z and n are as defined for Formula IV.        Solvents such as pyridine or pyridine/acetonitrile are suitable        for this reaction. The acid chlorides of Formula 11 are        available from the corresponding acids of Formula 7 wherein R¹        is H by known procedures such as chlorination with thionyl        chloride or oxalyl chloride.

Compounds of Formula IV can be prepared by the reaction ofbenzoxazinones of Formula 9 with C₁-C₄ alkylamines and (C₁-C₄alkyl)(methyl)amines of Formula 12 as outlined in Scheme 11.

-   -   wherein R⁶, R⁷, R^(8a), R^(8b), R⁹, X¹, Z and n are as        previously defined.        The reaction can be run neat or in a variety of suitable        solvents including acetonitrile, tetrahydrofuran, diethyl ether,        dichloromethane or chloroform with optimum temperatures ranging        from room temperature to the reflux temperature of the solvent.        The general reaction of benzoxazinones with amines to produce        anthranilamides is well documented in the chemical literature.        For a review of benzoxazinone chemistry see Jakobsen et al.,        Biorganic and Medicinal Chemistry 2000, 8, 2095-2103 and        references cited within. See also Coppola, J. Heterocyclic        Chemistry 1999, 36, 563-588.

1. A method for preparing a2-substituted-5-oxo-3-pyrazolidinecarboxylate compound of Formula I

wherein L is H, optionally substituted aryl, optionally substitutedtertiary alkyl, —C(O)R³, —S(O)₂R³ or —P(O)(R³)₂; R¹ is an optionallysubstituted carbon moiety; R^(2a) is H, OR⁴ or an optionally substitutedcarbon moiety; R^(2b) is H or an optionally substituted carbon moiety;each R³ is independently OR⁵, N(R⁵)₂ or an optionally substituted carbonmoiety; R⁴ is an optionally substituted carbon moiety; and each R⁵ isselected from optionally substituted carbon moieties; comprising:contacting a succinic acid derivative of Formula II

wherein X is a leaving group; and Y is a leaving group; with asubstituted hydrazine of Formula IIILNHNH₂   III in the presence of a suitable acid scavenger and solvent.2. The method of claim 1 wherein X is Cl, Br or I.
 3. The method ofclaim 2 wherein X is Br.
 4. The method of claim 1 wherein Y is Cl. 5.The method of claim 1 wherein R¹ is C₁-C₄ alkyl.
 6. The method of claim1 wherein the compound of Formula I is of Formula Ia

the compound of Formula II is of Formula IIa

and the compound of Formula III is of Formula IIIa

wherein each R⁹ is independently C₁-C₄ alkyl, C₂-C₄ alkenyl, C₂-C₄alkynyl, C₃-C₆ cycloalkyl, C₁-C₄ haloalkyl, C₂-C₄ haloalkenyl, C₂-C₄haloalkynyl, C₃-C₆ halocycloalkyl, halogen, CN, NO₂, C₁-C₄ alkoxy, C₁-C₄haloalkoxy, C₁-C₄ alkylthio, C₁-C₄ alkylsulfinyl, C₁-C₄ alkylsulfonyl,C₁-C₄ alkylamino, C₂-C₈ dialkylamino, C₃-C₆ cycloalkylamino, (C₁-C₄alkyl)(C₃-C₆ cycloalkyl)amino, C₂-C₄ alkylcarbonyl, C₂-C₆alkoxycarbonyl, C₂-C₆ alkylaminocarbonyl, C₃-C₈ dialkylaminocarbonyl orC₃-C₆ trialkylsilyl; Z is N or CR¹⁰; R¹⁰ is H or R⁹; and n is an integerfrom 0 to
 3. 7. The method of claim 6 wherein X is Br.
 8. The method ofclaim 6 wherein Y is Cl.
 9. The method of claim 6 wherein R¹ is CH₃. 10.A method of preparing a compound of Formula IV

wherein X¹ is halogen; R⁶ is CH₃, F, Cl or Br; R⁷ is F, Cl, Br, I, CN orCF₃; R^(8a) is H or C₁-C₄ alkyl; R^(8b) is H or CH₃; each R⁹ isindependently C₁-C₄ alkyl, C₂-C₄ alkenyl, C₂-C₄ alkynyl, C₃-C₆cycloalkyl, C₁-C₄ haloalkyl, C₂-C₄ haloalkenyl, C₂-C₄ haloalkynyl, C₃-C₆halocycloalkyl, halogen, CN, NO₂, C₁-C₄ alkoxy, C₁-C₄ haloalkoxy, C₁-C₄alkylthio, C₁-C₄ alkylsulfinyl, C₁-C₄ alkylsulfonyl, C₁-C₄ alkylamino,C₂-C₈ dialkylamino, C₃-C₆ cycloalkylamino, (C₁-C₄ alkyl)(C₃-C₆cycloalkyl)amino, C₂-C₄ alkylcarbonyl, C₂-C₆ alkoxycarbonyl, C₂-C₆alkylaminocarbonyl, C₃-C₈ dialkylaminocarbonyl or C₃-C₆ trialkylsilyl; Zis N or CR¹⁰; R¹⁰ is H or R⁹; and n is an integer from 0 to 3 using acompound of Formula Ia

wherein R¹ is an optionally substituted carbon moiety; characterized by:preparing said compound of Formula Ia by the method of claim
 6. 11. Themethod of claim 10 wherein R¹ is C₁-C₄ alkyl.
 12. The method of claim 11wherein Z is N, n is 1, and R⁹ is Cl or Br and is at the 3-position. 13.A composition comprising on a weight basis about 20 to 99% of thecompound of Formula II

wherein R¹ is an optionally substituted carbon moiety; R^(2a) is H, OR⁴or an optionally substituted carbon moiety; R^(2b) is H or an optionallysubstituted carbon moiety; R⁴ is an optionally substituted carbonmoiety; and X is Cl, Br or I; and Y is F, Cl, Br or I; provided thatwhen R^(2a) and R^(2b) are each H, and X and Y are each Cl then R¹ isother than benzyl and when R^(2a) and R^(2b) are each phenyl, and X andY are each Cl, then R¹ is other than methyl or ethyl.
 14. Thecomposition of claim 13 wherein R¹ is methyl; R^(2a) and R^(2b) are H; Xis Br; and Y is Cl.
 15. The composition of claim 13 wherein R¹ is ethyl;R^(2a) and R^(2b) are H; X is Br; and Y is Cl.
 16. A crystallinecomposition comprising at least about 90% by weight of the compound ofFormula VI

wherein R^(2a) and R^(2b) are H. X is Br and R¹ is methyl.